A wearable device (WD) may be usually connected to relay user equipment (Relay UE), such as a mobile phone, through Bluetooth, a wireless local area network (WLAN), or device-to-device (D2D), and then is connected to a base station through the relay user equipment, to receive a network service. In other words, a resource used by the WD to communicate with the base station through the relay user equipment needs to be mapped to a resource used by the relay UE to communicate with the base station.
In a mobile communication scenario, for example, when the WD and the relay UE move together from a cell 1 to a cell 2, if the cell 1 and the cell 2 are served by different base stations, both the WD and the relay UE need to be handed over from a base station 1 in the cell 1 to a base station 2 in the cell 2 to ensure that the WD can still transmit data through the relay UE. In this case, the WD and the relay UE each report a measurement report to a source base station (namely, the base station 1), to trigger the base station 1 to make a handover decision, send a handover request to a target base station, and finally separately hand over the WD and the relay UE to the target base station (namely, the base station 2) as two independent user equipment by using an radio resource control (RRC) reconfiguration procedure. In this case, when the WD reports a measurement report of the WD to the base station 2 again, the base station 2 is triggered to determine a resource mapping relationship between the WD and the relay UE, and hand over, by using another RRC reconfiguration procedure, the WD from a cellular link that is directly connected to the base station 2 to a trunk link that is indirectly connected to the base station 2 through the relay UE. In this way, the WD can subsequently transmit data with the base station 2 through the relay UE.
It can be learned that in the foregoing cross-base station handover procedure, the WD needs to report the measurement report to the source base station, to trigger the source base station to make a handover decision. Then, the WD is handed over to the target base station by using the RRC reconfiguration procedure, reports the measurement report to the target base station, to trigger the target base station to make a decision on handing over the WD from the cellular link that is directly connected to the base station to the trunk link that is indirectly connected to the base station by using the relay user equipment, and re-establishes a resource mapping relationship with the relay UE by using the RRC reconfiguration procedure. Consequently, an amount of signaling interaction is relatively large, and a handover procedure is relatively tedious, which is unconducive to power saving of a WD with a relatively small volume and a limited battery capacity.